Halina Przymusinska Teodor C. Przymusinski Hirohisa Seki Soundness and Completeness of Partial Deductions for Well-Founded Semantics. 1-12 1992 conf/lpar/1992 LPAR db/conf/lpar/lpar92.html#PrzymusinskaPS92 http://dx.doi.org/10.1007/BFb0013044